coyote: CGBLENDIMAGE

Description
This alpha blends two 24-bit images and displays them with the cgImage command.
The program requires the `Coyote Library `
to be installed on your machine.
Categories
Graphics
Params
foregroundImage: in, required, type=truecolor
     A 24-bit foreground image with the same dimensions as the background image.
backgroundImage: in, required, type=truecolor    
     A 24-bit background image with the same dimensions as the foreground image.
Keywords
alpha: in, optional, type=float, default=0.5
     A number between 0 and 1 that indicates the percentage of the foreground image
     to alpha-blend into the background image. For example, ALPHA=0.2 will give
     a weigth of 20% to the foreground image pixels and 80% to the background image
     pixels. 
indow: in, optional, type=intarr
     A one-, two-, or three-element array giving the window index numbers for
     the foreground, background, and display windows, repectively. If one-element,
     the foreground image is retrieved from that window and displayed in the current
     window. If two elements, the foreground and background images are obtained from
     the first two elements, respectively, and a new third display window is opened.
     This is the same for three elements, except the third element is used to specify
     the display window.
_ref_extra: in, optional
     Any keyword appropriate for the cgImage command is also accepted by keyword
     inheritance.
Author
FANNING SOFTWARE CONSULTING::
    David W. Fanning 
    1645 Sheely Drive
    Fort Collins, CO 80526 USA
    Phone: 970-221-0438
    E-mail: david@idlcoyote.com
    Coyote's Guide to IDL Programming: http://www.idlcoyote.com
History
Change History::
   Written by: David W. Fanning, 26 May 2009.
   Added the WINDOW keyword. 16 February 2012. DWF.
Copyright
Copyright (c) 2009-2012, Fanning Software Consulting, Inc.